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Genetic Disorders & Testing

Warning: sensitive material. Genetic Disorders & Testing. Polydactyl- dominant trait. review. What is a mutation?. Results of a mutation?  . 2 types of mutations Gene or Chromosomal. Review Types of Gene mutations. 1. Point mutation: change in one nitrogen base in DNA;

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Genetic Disorders & Testing

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  1. Warning: sensitive material Genetic Disorders & Testing Polydactyl- dominant trait

  2. review What is a mutation? Results of a mutation?   2 types of mutations Gene or Chromosomal

  3. ReviewTypes of Gene mutations • 1. Point mutation: change in one nitrogen base in DNA; • Ex. Substitution • 2. Frameshift Mutation • Ex. insertion or deletion of a base • shifts entire sequence for translation

  4. review Chromosomal Mutation • Change in # or structure of the chromosome • Mitosis & meiosis • usually not passed on because zygote dies Ex. Deletion Inversion Duplication translocation

  5. Nondisjunctionoccurs when a chromosome pair fails to separate properly during meiosis-can happen to any chromosome pair • 2. Trisomy: when gamete has one more chromosome than it should • 47 chromosomes( need 46) • Ex: Down’s syndrome, extra #21 2 types: • 1. Monosomy: when gamete has one less chromosome than it should • only 45 chromosomes (need 46) • Ex: Turner syndrome-occurs only in females Don’t forget: you have 23 pairs(46 chromosomes) in each cell in your body

  6. GENETIC DISORDERS • THESE ARE THE ONES YOU NEED TO KNOW FOR THE TEST! • Autosome- lst 22 pairs of chromosomes • Sex-linked- 23rd pair

  7. Autosomal Recessive Disorders Disorder: Progeria Facts: rapid aging disease, Caused by point mutation Symptoms: thin, bald, old-looking skin Incidence: rare (live to teens or maybe 30’s) Treatments: none

  8. Autosomal Recessive Disorders Disorder: Albinism Facts: can be caused by a autosomal recessive, autosomal dominant or sex-linked trait; point mutation • Symptoms: absence of pigment in hair, skin, eyes; • defect of melanin production • Photophobic- sunlight painful to eyes Incidence: common in European descent; less common in African Americans & Asians Treatments: none

  9. Autosomal Recessive Disorders Disorder: PKU Facts: missing an enzyme that breaks down Phenyalanine (in milk) /it accumulates in the central nervous system Caused by a point mutation Symptoms: can cause mental retardation, abnormal growth patterns Incidence: rare in African Americans & Japanese; more common in Irish Treatments: test newborns- change diet

  10. Autosomal Recessive Disorders Disorder: CF- Cystic Fibrosis Facts: mucus in lungs & digestive tract is very thick ; caused by point mutation Symptoms: makes breathing & digestion difficult Incidence: most common in Caucasians(whites) 1 in 2000 white; 1 in 25 carry recessive allele. Treatments: frequent lungs infections, daily therapy is needed to loosen & remove mucus

  11. Autosomal Recessive Disorders Disorder: Tay-Sachs Facts: disorder of central nervous system: brain & spinal cord • missing an enzyme which breaks down lipids; accumulates in brain Symptoms: everything goes in reverse; deteriorates Incidence: 1 in 27 Jews, Cajuns(Lousiana), & French-Canadians are carriers Treatments: none; happens within 1st year most children don’t live past 5

  12. Autosomal Recessive Disorder/ Codominance Disorder: Sickle-Cell Anemia Facts: sickle-shaped blood cells block/clot up blood vessels; point mutation Symptoms: pain in joints, anemia, weakness, jaundice Incidence: 1 in 375 African Americans Treatments: bone marrow transplants, medicines

  13. Autosomal Dominant Disorders Disorder: Huntington’s Disease Facts: degeneration of nerve cells in the brain because of faulty gene on chromosome # 4(point mutation) Symptoms: mood swings, depression, memory loss, decline in movements & speech Death usually occurs 10-20 years after onset of symptoms. Symptoms begin between ages of 30-50. Incidence:Every child of a parent with the disorder has a 50% chance of inheriting Huntington's Disease. Treatments: none *Mother murdered/assisted suicide/ her sons in the nursing home here in Ga.

  14. Autosomal Dominant Disorders Disorder: Achondroplasia Facts: stunted bone growth; type of Dwarfism Point mutations Symptoms: Torso is normal but arms and legs are short. Incidence: 1 out of 25000 • Only heterozygotes have this disorder. • Homozygous dominant condition results in death of the embryo. Treatments:none

  15. Aneuploidy(caused by Nondisjunction) Disorder: Down’s Syndrome (Trisomy 21) Facts: most common reason for mental retardation; chromosomes failed to separate Symptoms: mental retardation, slanted eyes Incidence: 1 in 900; most cases not inherited Treatments: none

  16. Aneuploidy(caused by Nondisjunction/ Trisomy) Disorder: Klinefelter Syndrome Facts: XXY - Trisomy- chromosomes failed to separate Symptoms: male, taller than average, longer limbs, sterile, may have some mental retardation Incidence: Treatments: none

  17. Aneuploidy(caused byNondisjunction/ Monosomy) Disorder: Turner’s Syndrome Facts: female, only 1 X b/c of Nondisjunction Symptoms: sterile, lack of sexual development(no ovaries), short stature Incidence: Treatments: hormone Therapy given estrogen And growth hormone.

  18. Chromosomal mutation Disorders Disorder: Cri Du Chat Syndrome Facts: missing piece of chromosome # 5 (deletion) Symptoms: mental retardation, high-pitched cry that sounds like a cat. Incidence: avg. 1 in 40, 000 Treatments: none

  19. Sex-linked Disorders*write XmXm , XmY*most disorders are x-linked, recessive Disorder: Muscular Dystrophy (MD) (duchenne’s only) Facts: recessive, x-linked; many types of MD Symptoms: muscle loss & weakness Incidence: mainly in males; all ethnic groups have an equal chance of MD Treatments: physical therapy , braces, wheelchair

  20. Sex-linked Disorders Disorder: Hemophilia Facts: recessive, x-linked; blood does not have clotting factors Symptoms: bleed excessively or to death Incidence: mainly in males ; Royal Family Treatments: inject themselves with purified clotting factors to prevent or stop bleeding

  21. Sex-linked Disorders Disorder: Color-blindness Facts: recessive, x-linked disorder; Cones in eyes(color receptors) are absent or lack of pigment Symptoms: cannot tell difference between certain colors Incidence: mainly in males- passed from mother; • red-green color blindness most common • Seeing only black/white is rare Treatments: none

  22. 1. Karyotyping: pictures of chromosomes are matched up according to size 4 Methods of detection

  23. methods of detection cont • 2. Ultrasound: sound waves/ image. Used to detect abnormalities of limbs, organs, etc. • 3. Amniocentesis: fluid surrounding the fetus is drawn out by needle, fetal cells collected/ grown Chromosomes karyotyped

  24. 4. Chorion villi sampling: a sample of the chorion (membrane surrounding fetus) is taken, chemical tests and karyotyping are performed

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